1. Field of the Invention
The invention relates to microphones, and more particularly to microphone arrays.
2. Description of the Related Art
A microphone array comprises multiple microphones converting sounds received to multiple electrical signals. Because the electrical signals generated by a microphone array have phase difference and gain difference therebetween due to diversity of location, a processor can properly tune specific properties of the electric signals according to the phase difference and gain difference. For example, a processor can improve sensitivity of the microphone array to sounds from specific directions through calculations based on phase differences between the electrical signals. Thus, microphone arrays have more flexible application in high-level sound processing.
FIG. 1 shows a conventional microphone array with microphones connected in parallel to a host. In an embodiment, the host is a processor. The microphone array comprises two microphones 102 and 104. The microphones 102 and 104 respectively convert sounds S1 and S2 to electrical signals. The electrical signals generated by the microphones 102 and 104 are transferred to a host 106 together through a single data path, a configuration referred to as parallel connection. The host 106 provides a clock signal for the microphones 102 and 104. The microphone 102 outputs data at a rising edge of the clock signal, and the microphone 104 outputs data at a falling edge of the clock signal, thus the data path is shared by the two microphones of the array.
Although two microphones of a microphone array can share a data path connecting the host and the microphone array, microphone arrays comprising more than two microphones require extra signal paths leading to the host. A host, such as a processor, however, has only a limited number of data buses and cannot allocate a great number thereof to a microphone array. In addition, data processing loading of a host increases with the number of the microphones connected to the host, because more microphones generate more electrical input signals to the host. Thus, a microphone array reducing data processing loading and bus number of the host is required.